Predictors of acute hematologic toxicity attributable to palliative radiotherapy: Analysis of patient characteristics and bone marrow dose-volume parameters.

PURPOSE: As predictors of hematologic toxicity (HT) after palliative radiotherapy (RT) have been studied insufficiently, we explored predictors of leukopenia, neutropenia, and thrombocytopenia attributable to palliative RT.

METHODS: We retrospectively assessed patients with various solid tumors who had received palliative RT at our institution. Excluded from our study were patients who had undergone chemotherapy from one month before to one month after the start of RT. To measure the bone marrow dose, all bones were delineated, and the absolute volume of bone marrow that had received 5, 10, 20, and 30 Gy was recorded. Univariate and multivariate logistic regression analysis was performed to identify variables associated with leukopenia, neutropenia, or thrombocytopenia of grade 2 or higher (HT2+).

RESULTS: Of 68 patients, 17 (25%) developed HT2+. Grade ≥ 2 leukopenia developed in 13 patients (19%), neutropenia in 8 (12%), and thrombocytopenia in 6 (9%). Only one patient experienced ≥ grade 3 toxicity. The median baseline and nadir white blood cell count (WBC) was 6.950 and 4.650x109/l, respectively; the absolute neutrophil count (ANC) was 5.236 and 3.307x109/l, respectively, and the platelet count was 249 and 177.5x109/l, respectively. Multivariate analysis revealed that female gender and a lower baseline WBC and ANC were significant independent predictors of HT2+. No bone marrow dose-volume parameter was a significant predictor of HT2+.

CONCLUSIONS: Overall, HT was relatively mild. Female gender and lower baseline WBC and ANC may be predictors of HT elicited by palliative RT.